A transformer digital oil level monitoring method and system

Abstract

The application relates to the technical field of transformer data monitoring, and discloses a transformer digital oil level monitoring method and system, which compares the real-time oil level height of an oil storage tank with a preset oil level height threshold range to monitor the real-time oil level of the oil storage tank, and compares the real-time oil volume of the oil storage tank with the theoretical oil volume of the oil storage tank under the current oil temperature horizontally, and performs oil level abnormality alarm, and compares the real-time oil volume of the oil storage tank with the historical oil volume under the current oil temperature and the same environment temperature vertically, and performs oil level abnormality alarm, so that multi-dimensional monitoring of the transformer oil level under the oil temperature and the environment temperature can be realized, and the accuracy of the transformer oil level monitoring result is improved.

Description

Technical Field

[0001] This invention relates to the field of transformer data monitoring technology, and in particular to a digital oil level monitoring method and system for transformers. Background Technology

[0002] Transformer oil plays a crucial role in the insulation and cooling of oil-immersed transformers. If the transformer oil level is too high, excessive pressure within the tank may occur under high temperature or heavy load conditions, leading to oil overflow or activation of the pressure relief valve. Conversely, if the oil level is too low, high-voltage components may be exposed without oil protection, resulting in breakdown, discharge, and transformer damage. Furthermore, the oil level reflects the tank's sealing condition, facilitating the timely detection of oil leaks or seepage. Therefore, timely and accurate monitoring of the oil level is essential for the safe operation of transformers.

[0003] Traditional transformer oil level monitoring is configured to issue a high oil level alarm when the actual oil level exceeds a high oil level threshold and a low oil level alarm when the actual oil level falls below a low oil level threshold. This type of alarm setting cannot provide timely feedback on oil level anomalies; it only triggers an alarm when the oil level changes to the alarm threshold, by which time the anomaly is already quite severe. Before the oil level changes to the threshold, monitoring relies on routine inspections by operators: operators use the transformer's factory oil temperature-level curve to determine whether the current oil level is normal based on the current oil temperature.

[0004] With the development of pressure sensor technology and the requirements of smart grid development, digital oil level gauges and acquisition devices that reflect oil level using transformer oil pressure have been proposed.

[0005] Chinese invention patent application CN115116705A discloses a transformer oil tank status monitoring system. By measuring the pressure of the transformer oil and calculating the oil density, the real-time oil level is calculated by combining the real-time measured oil level with the volume of the transformer body and the size of the oil tank, thereby enabling real-time monitoring of the oil level in the oil tank.

[0006] Chinese invention patent application with publication number CN114662322A discloses a method and system for online monitoring and fault diagnosis of transformer oil level anomalies. The method obtains real-time oil temperature and oil level data of the transformer, generates an actual oil temperature and oil level curve, calculates the error value between the actual curve and the theoretical oil temperature and oil level curve, and determines that the real-time data is abnormal when the error value exceeds a preset range.

[0007] Research and development revealed that while the two aforementioned technical solutions can effectively improve the sensitivity of detecting oil temperature deviations, these methods still have the following problems:

[0008] 1) It is necessary to obtain the total oil volume of the transformer so as to calculate the change in oil volume based on the coefficient of thermal expansion of the oil. Generally, the total oil volume is marked on the nameplate of the transformer, but this data differs from the actual total oil volume of the transformer, and this difference is difficult to eliminate effectively.

[0009] 2) The transformer oil temperature and oil level change curve is generally provided by the transformer manufacturer. However, this change curve is usually given by the manufacturer based on the design data, and there is a difference between it and the actual oil temperature and oil level change curve of the transformer. This difference is also difficult to eliminate effectively.

[0010] 3) During transformer operation, the oil temperature at the top, middle and bottom of the transformer is not the same. Under high load, the transformer generates a lot of heat and the oil temperature difference at different locations is relatively large. Therefore, calculating the volume change of transformer oil based solely on the top oil temperature will result in a large error.

[0011] In summary, there are currently significant errors in the results of transformer oil level monitoring, resulting in poor accuracy of the monitoring results. Summary of the Invention

[0012] This invention provides a digital oil level monitoring method and system for transformers, which solves the technical problem that the monitoring results of transformer oil levels have large errors, resulting in poor accuracy of the monitoring results.

[0013] In view of this, the first aspect of the present invention provides a digital oil level monitoring method for transformers, comprising the following steps:

[0014] Obtain the real-time oil level in the oil tank;

[0015] The real-time oil level is compared with a preset oil level threshold range. If the real-time oil level is within the preset oil level threshold range, proceed to the next step. If the real-time oil level is not within the preset oil level threshold range, an oil level abnormality alarm is issued.

[0016] Obtain the real-time oil level in the oil storage tank;

[0017] Calculate the theoretical oil volume of the oil tank at the current oil temperature, obtain the first oil volume difference between the real-time oil volume and the theoretical oil volume of the oil tank, determine whether the first oil volume difference is greater than a preset first oil volume difference threshold, if the first oil volume difference is greater than the preset first oil volume difference threshold, then issue an oil level abnormality alarm, if the first oil volume difference is not greater than the preset first oil volume difference threshold, then proceed to the next step;

[0018] The system obtains a second oil volume difference between the real-time oil volume of the oil tank and the historical oil volume at the same oil temperature and ambient temperature. It then determines whether the second oil volume difference is greater than a preset second oil volume difference threshold. If the second oil volume difference is greater than the preset second oil volume difference threshold, an oil level anomaly alarm is triggered. If the second oil volume difference is not greater than the preset second oil volume difference threshold, the system returns to the step of obtaining the real-time oil level of the oil tank.

[0019] Optionally, the steps for obtaining the real-time oil level in the oil storage tank specifically include:

[0020] The oil pressure in the oil tank is measured by a digital oil level gauge, and the real-time oil level H in the oil tank is calculated using the following formula. 油 :

[0021] H 油 =P(1+αt) / ρ 油 g

[0022] In the formula, P is the oil pressure measured by the digital oil level gauge, α is the thermal expansion coefficient of the transformer oil, t is the oil temperature, and ρ is the oil temperature measured by the digital oil level gauge. 油 ρ is the density of transformer oil at 0℃, and g is the acceleration due to gravity.

[0023] Optionally, when the oil storage tank adopts a horizontal cylindrical tank structure, the step of obtaining the real-time oil volume of the oil storage tank specifically includes:

[0024] The per-unit value of the oil level in the oil tank is calculated using the following formula:

[0025] h=(H 油 -H 底 ) / D

[0026] In the formula, h is the per-unit value of the oil tank height, H 底 D is the installation height of the pressure sensor relative to the bottom of the oil tank, and D is the diameter of the oil tank.

[0027] The oil volume ratio in the oil tank is calculated using the following formula:

[0028] When h < 0.5, the corresponding oil volume ratio at the high oil level h is:

[0029]

[0030] When h ≥ 0.5, the corresponding oil volume ratio at the high oil level h is:

[0031]

[0032] The real-time oil volume V in the oil tank is calculated using the following formula. 油 for:

[0033] V 油 =sV储油柜 =πsR 2 L

[0034] In the formula, s is the proportion of oil in the oil tank, and V 储油柜 R is the total volume of the oil tank, R is the radius of the oil tank, and L is the length of the oil tank.

[0035] When the oil storage tank adopts a vertical corrugated oil storage tank structure, the steps for obtaining the real-time oil volume of the oil storage tank specifically include:

[0036] The real-time oil volume V of the oil tank is obtained through the following formula. 油 :

[0037] V 油 =S 俯 H 油 =S 俯 P(1+αt) / ρ 油 g

[0038] In the formula, S 俯 This indicates the cross-sectional area of ​​the oil storage tank when viewed from above.

[0039] Optionally, the steps for calculating the theoretical oil volume in the oil tank at the current oil temperature specifically include:

[0040] The theoretical oil volume V of the oil tank at the current oil temperature is calculated using the following formula. 油算 for:

[0041] V 油算 =V 油0 +αtV 本

[0042] In the formula, V 油0 V represents the standard oil volume in the oil tank at 0℃, t represents the oil temperature sampling value, and V represents the standard oil volume in the tank at 0℃. 本 This represents the total transformer oil volume in the oil conservator at 0℃.

[0043] Optionally, this method also includes:

[0044] When it is detected that there is no historical oil volume in the historical oil volume database that has the same oil temperature and ambient temperature as the real-time oil volume, if the first oil volume difference between the real-time oil volume and the theoretical oil volume of the oil tank does not trigger an oil level abnormality alarm, the real-time oil volume of the oil tank is stored as historical oil volume data at the corresponding oil temperature and ambient temperature in the historical oil volume database.

[0045] The historical oil volume database is accessed based on the oil temperature and ambient temperature closest to the real-time oil volume. The interpolated historical oil volume is then used as the historical oil volume.

[0046] Secondly, the present invention also provides a digital oil level monitoring system for transformers, comprising:

[0047] The oil level acquisition module is used to acquire the real-time oil level height of the oil tank;

[0048] The oil level monitoring module is used to compare the real-time oil level height with a preset oil level height threshold range. If the real-time oil level height is within the preset oil level height threshold range, the oil quantity acquisition module is executed. If the real-time oil level height is not within the preset oil level height threshold range, an oil level abnormality alarm is issued.

[0049] The oil quantity acquisition module is used to acquire the real-time oil quantity of the oil storage tank.

[0050] The first oil level monitoring module is used to calculate the theoretical oil level of the oil tank at the current oil temperature, obtain the first oil level difference between the real-time oil level and the theoretical oil level, determine whether the first oil level difference is greater than a preset first oil level difference threshold, and if the first oil level difference is greater than the preset first oil level difference threshold, an oil level abnormality alarm is issued; if the first oil level difference is not greater than the preset first oil level difference threshold, the second oil level monitoring module is executed.

[0051] The second oil level monitoring module is used to obtain the second oil level difference between the real-time oil level of the oil tank and the historical oil level at the same current oil temperature and ambient temperature, and to determine whether the second oil level difference is greater than a preset second oil level difference threshold. If the second oil level difference is greater than the preset second oil level difference threshold, an oil level abnormality alarm is issued.

[0052] Optionally, the oil level acquisition module is specifically used to measure the oil pressure of the oil tank using a digital oil level gauge, and calculate the real-time oil level height H of the oil tank using the following formula. 油 :

[0053] H 油 =P(1+αt) / ρ 油 g

[0054] In the formula, P is the oil pressure measured by the digital oil level gauge, α is the thermal expansion coefficient of the transformer oil, t is the oil temperature, and ρ is the oil temperature measured by the digital oil level gauge. 油 ρ is the density of transformer oil at 0℃, and g is the acceleration due to gravity.

[0055] Optionally, when the oil storage tank adopts a horizontal cylindrical tank structure, the oil quantity acquisition module specifically includes:

[0056] The per-unit value calculation module is used to calculate the per-unit value of the oil level at the height of the oil tank using the following formula:

[0057] h=(H 油 -H 底 ) / D

[0058] In the formula, h is the per-unit value of the oil tank height, H底 D is the installation height of the pressure sensor relative to the bottom of the oil tank, and D is the diameter of the oil tank.

[0059] The oil volume ratio calculation module is used to calculate the oil volume ratio of the oil tank using the following formula:

[0060] When h < 0.5, the corresponding oil volume ratio at the high oil level h is:

[0061]

[0062] When h ≥ 0.5, the corresponding oil volume ratio at the high oil level h is:

[0063]

[0064] The real-time oil volume calculation module is used to calculate the real-time oil volume V of the oil tank using the following formula. 油 for:

[0065] V 油 =sV 储油柜 =πsR 2 L

[0066] In the formula, s is the proportion of oil in the oil tank, and V 储油柜 R is the total volume of the oil tank, R is the radius of the oil tank, and L is the length of the oil tank.

[0067] When the oil storage tank adopts a vertical corrugated oil storage tank structure, the steps for obtaining the real-time oil volume of the oil storage tank specifically include:

[0068] The real-time oil volume V of the oil tank is obtained through the following formula. 油 :

[0069] V 油 =S 俯 H 油 =S 俯 P(1+αt) / ρ 油 g

[0070] In the formula, S 俯 This indicates the cross-sectional area of ​​the oil storage tank when viewed from above.

[0071] Optionally, the first oil quantity monitoring module includes:

[0072] The theoretical oil volume calculation module is used to calculate the theoretical oil volume V of the oil tank at the current oil temperature using the following formula. 油算 for:

[0073] V 油算 =V 油0 +αtV 本

[0074] In the formula, V 油0V represents the standard oil volume in the oil tank at 0℃, t represents the oil temperature sampling value, and V represents the standard oil volume in the tank at 0℃. 本 This represents the total transformer oil volume in the oil conservator at 0℃.

[0075] Optionally, this system also includes:

[0076] The historical oil volume storage module is used to store the real-time oil volume of the oil tank as historical oil volume data at the corresponding oil temperature and ambient temperature in the historical oil volume database when it is detected that there is no historical oil volume at the same oil temperature and ambient temperature as the real-time oil volume. If the first oil volume difference between the real-time oil volume and the theoretical oil volume of the oil tank does not trigger an oil level abnormality alarm, the module will store the real-time oil volume of the oil tank as historical oil volume data at the corresponding oil temperature and ambient temperature in the historical oil volume database.

[0077] The historical oil volume calculation module is used to call the historical oil volume at the oil temperature and ambient temperature that is closest to the real-time oil volume in the historical oil volume database, and obtain the corresponding interpolated historical oil volume as the historical oil volume by interpolation calculation.

[0078] As can be seen from the above technical solutions, the present invention has the following advantages:

[0079] This invention monitors the real-time oil level of the transformer oil conservator by acquiring the real-time oil level height and comparing it with a preset oil level height threshold range. It also performs a horizontal comparison between the real-time oil volume and the theoretical oil volume at the current oil temperature, issuing an oil level anomaly alarm. Furthermore, it performs a vertical comparison between the real-time oil volume and historical oil volumes at the same oil temperature and ambient temperature, also issuing an oil level anomaly alarm. This multi-dimensional monitoring of the transformer oil level under both oil temperature and ambient temperature conditions improves the accuracy of transformer oil level monitoring results. Attached Figure Description

[0080] Figure 1 A flowchart of a digital oil level monitoring method for transformers provided in an embodiment of the present invention;

[0081] Figure 2 A front view of the oil level height of the horizontal cylindrical tank structure provided in an embodiment of the present invention.

[0082] Figure 3 This is a front view of the oil level height of the vertical corrugated oil tank structure provided in an embodiment of the present invention.

[0083] Figure 4 This is a schematic diagram of a digital oil level monitoring system for transformers provided in an embodiment of the present invention. Detailed Implementation

[0084] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0085] For easier understanding, please refer to Figure 1 The present invention provides a digital oil level monitoring method for transformers, comprising the following steps:

[0086] S1. Obtain the real-time oil level in the oil tank;

[0087] In one example, the oil pressure in the oil tank is measured using a digital oil level gauge, and the real-time oil level H in the oil tank is calculated using the following formula. 油 :

[0088] H 油 =P(1+αt) / ρ 油 g

[0089] In the formula, P is the oil pressure measured by the digital oil level gauge, α is the thermal expansion coefficient of the transformer oil, t is the oil temperature, and ρ is the oil temperature measured by the digital oil level gauge. 油 ρ is the density of transformer oil at 0℃, and g is the acceleration due to gravity.

[0090] S2. Compare the real-time oil level with the preset oil level threshold range. If the real-time oil level is within the preset oil level threshold range, proceed to the next step. If the real-time oil level is not within the preset oil level threshold range, issue an oil level anomaly alarm.

[0091] Specifically, if the real-time oil level is greater than the high oil level threshold, a high oil level event is recorded and a high oil level anomaly alarm is triggered; if the real-time oil level is less than the low oil level threshold, a low oil level event is recorded and a low oil level anomaly alarm is triggered.

[0092] S3. Obtain the real-time oil level in the oil tank;

[0093] S4. Calculate the theoretical oil volume of the oil tank at the current oil temperature, obtain the first oil volume difference between the real-time oil volume and the theoretical oil volume, and determine whether the first oil volume difference is greater than the preset first oil volume difference threshold. If the first oil volume difference is greater than the preset first oil volume difference threshold, an oil level abnormality alarm is issued. If the first oil volume difference is not greater than the preset first oil volume difference threshold, proceed to the next step.

[0094] Among them, the real-time oil volume is compared with the theoretical oil volume of the oil tank at the current oil temperature to realize the functions of horizontal oil volume anomaly judgment, recording and alarm.

[0095] S5. Obtain the second oil volume difference between the real-time oil volume of the oil tank and the historical oil volume at the same oil temperature and ambient temperature. Determine whether the second oil volume difference is greater than the preset second oil volume difference threshold. If the second oil volume difference is greater than the preset second oil volume difference threshold, then issue an oil level abnormality alarm. If the second oil volume difference is not greater than the preset second oil volume difference threshold, then return to step S1.

[0096] Among them, the real-time oil volume is compared longitudinally with the historical oil volume at the same oil temperature and ambient temperature to realize the functions of longitudinal anomaly judgment, recording and alarm of oil volume.

[0097] It should be noted that the digital oil level monitoring method for transformers provided by this invention acquires the real-time oil level height of the oil conservator, compares the real-time oil level height with a preset oil level height threshold range, thereby monitoring the real-time oil level of the oil conservator. It also performs a horizontal comparison between the real-time oil volume of the oil conservator and the theoretical oil volume of the oil conservator at the current oil temperature, and issues an oil level anomaly alarm. Furthermore, it performs a vertical comparison between the real-time oil volume of the oil conservator and the historical oil volume at the same oil temperature and ambient temperature, and issues an oil level anomaly alarm. This enables multi-dimensional monitoring of the transformer oil level under both oil temperature and ambient temperature, improving the accuracy of the transformer oil level monitoring results.

[0098] In one specific embodiment, such as Figure 2 As shown, when the oil storage tank adopts a horizontal cylindrical tank structure, step S3 specifically includes:

[0099] S301. The per-unit value of the oil level at the height of the oil tank is calculated using the following formula:

[0100] h=(H 油 -H 底 ) / D

[0101] In the formula, h is the per-unit value of the oil tank height, H 底 D is the installation height of the pressure sensor relative to the bottom of the oil tank, and D is the diameter of the oil tank.

[0102] S302. The oil volume ratio in the oil tank is calculated using the following formula:

[0103] When h < 0.5, the corresponding oil volume ratio at the high oil level h is:

[0104]

[0105] When h ≥ 0.5, the corresponding oil volume ratio at the high oil level h is:

[0106]

[0107] S303. Calculate the real-time oil volume V in the oil storage tank using the following formula. 油for:

[0108] V 油 =sV 储油柜 =πsR 2 L

[0109] In the formula, s is the proportion of oil in the oil tank, and V 储油柜 R is the total volume of the oil tank, R is the radius of the oil tank, and L is the length of the oil tank.

[0110] like Figure 3 As shown, when the oil storage tank adopts a vertical corrugated oil storage tank structure, the specific steps for obtaining the real-time oil volume of the oil storage tank include:

[0111] The real-time oil volume V of the oil tank is obtained through the following formula. 油 :

[0112] V 油 =S 俯 H 油 =S 俯 P(1+αt) / ρ 油 g

[0113] In the formula, S 俯 This indicates the cross-sectional area of ​​the oil storage tank when viewed from above.

[0114] In one specific embodiment, the step of calculating the theoretical oil volume of the oil tank at the current oil temperature specifically includes:

[0115] The theoretical oil volume V of the oil tank at the current oil temperature is calculated using the following formula. 油算 for:

[0116] V 油算 =V 油0 +αtV 本

[0117] In the formula, V 油0 V represents the standard oil volume in the oil tank at 0℃, t represents the oil temperature sampling value, and V represents the standard oil volume in the tank at 0℃. 本 This represents the total transformer oil volume in the oil conservator at 0℃.

[0118] In one specific embodiment, the method further includes:

[0119] S41. When it is detected that there is no historical oil volume in the historical oil volume database that has the same oil temperature and ambient temperature as the real-time oil volume, if the first oil volume difference between the real-time oil volume and the theoretical oil volume in the oil tank does not trigger an oil level abnormality alarm, the real-time oil volume in the oil tank is stored as the historical oil volume data at the corresponding oil temperature and ambient temperature in the historical oil volume database.

[0120] S42. Call the historical oil volume at the temperature and ambient temperature that is closest to the real-time oil volume in the historical oil volume database, and obtain the corresponding interpolated historical oil volume as the historical oil volume by interpolation calculation.

[0121] Understandably, historical oil volume data is only used for comparison and is discarded after comparison, without being stored in the historical oil volume database. This not only reduces the system's storage pressure but also ensures that all stored historical oil volume data is accurate and valid.

[0122] Users can set the storage intervals for oil temperature and ambient temperature according to their data storage space and accuracy requirements. In one example, the storage intervals for oil temperature (N1) and ambient temperature (N2) are set separately. The current measured oil temperature (t1) is read, and it is determined whether the current measured oil temperature (t1) is an integer multiple of the oil temperature storage interval (N1). If not, the process ends. If yes, the current ambient temperature (T1) is read, and it is determined whether the current ambient temperature (T1) is an integer multiple of the ambient temperature storage interval (N2). If not, the process ends. If yes, it is determined whether there is an oil volume record under the current measured oil temperature (t1) and current ambient temperature (T1). If not, the process ends. If yes, the current oil volume is stored as historical oil volume.

[0123] The above is a detailed description of an embodiment of a digital oil level monitoring method for transformers provided by the present invention. The following is a detailed description of an embodiment of a digital oil level monitoring system for transformers provided by the present invention.

[0124] For easier understanding, please refer to Figure 4 The present invention provides a digital oil level monitoring system for transformers, comprising:

[0125] The oil level acquisition module 10 is used to acquire the real-time oil level height of the oil tank;

[0126] The oil level monitoring module 20 is used to compare the real-time oil level height with the preset oil level height threshold range. If the real-time oil level height is within the preset oil level height threshold range, the oil quantity acquisition module 30 is executed. If the real-time oil level height is not within the preset oil level height threshold range, an oil level abnormality alarm is issued.

[0127] The oil quantity acquisition module 30 is used to acquire the real-time oil quantity of the oil storage tank;

[0128] The first oil quantity monitoring module 40 is used to calculate the theoretical oil quantity of the oil tank at the current oil temperature, obtain the first oil quantity difference between the real-time oil quantity of the oil tank and the theoretical oil quantity, determine whether the first oil quantity difference is greater than the preset first oil quantity difference threshold, and if the first oil quantity difference is greater than the preset first oil quantity difference threshold, then an oil level abnormality alarm is issued; if the first oil quantity difference is not greater than the preset first oil quantity difference threshold, then the second oil quantity monitoring module 50 is executed.

[0129] The second oil level monitoring module 50 is used to obtain the difference between the real-time oil level in the oil tank and the historical oil level at the same current oil temperature and ambient temperature, and to determine whether the difference between the second oil level and the historical oil level is greater than a preset second oil level difference threshold. If the difference between the second oil level and the historical oil level is greater than the preset second oil level difference threshold, an oil level abnormality alarm is triggered.

[0130] In one specific embodiment, the oil level acquisition module is specifically used to measure the oil pressure of the oil tank using a digital oil level gauge, and calculate the real-time oil level height H of the oil tank using the following formula. 油 :

[0131] H 油 =P(1+αt) / ρ 油 g

[0132] In the formula, P is the oil pressure measured by the digital oil level gauge, α is the thermal expansion coefficient of the transformer oil, t is the oil temperature, and ρ is the oil temperature measured by the digital oil level gauge. 油 ρ is the density of transformer oil at 0℃, and g is the acceleration due to gravity.

[0133] In one specific embodiment, when the oil storage tank adopts a horizontal cylindrical tank structure, the oil quantity acquisition module specifically includes:

[0134] The per-unit value calculation module is used to calculate the per-unit value of the oil level at the height of the oil tank using the following formula:

[0135] h=(H 油 -H 底 ) / D

[0136] In the formula, h is the per-unit value of the oil tank height, H 底 D is the installation height of the pressure sensor relative to the bottom of the oil tank, and D is the diameter of the oil tank.

[0137] The oil volume ratio calculation module is used to calculate the oil volume ratio of the oil tank using the following formula:

[0138] When h < 0.5, the corresponding oil volume ratio at the high oil level h is:

[0139]

[0140] When h ≥ 0.5, the corresponding oil volume ratio at the high oil level h is:

[0141]

[0142] The real-time oil volume calculation module is used to calculate the real-time oil volume V of the oil tank using the following formula. 油 for:

[0143] V 油 =sV 储油柜 =πsR 2 L

[0144] In the formula, s is the proportion of oil in the oil tank, and V 储油柜 R is the total volume of the oil tank, R is the radius of the oil tank, and L is the length of the oil tank.

[0145] When the oil storage tank adopts a vertical corrugated oil storage tank structure, the specific steps for obtaining the real-time oil volume of the oil storage tank include:

[0146] The real-time oil volume V of the oil tank is obtained through the following formula. 油 :

[0147] V 油 =S 俯 H 油 =S 俯 P(1+αt) / ρ 油 g

[0148] In the formula, S 俯 This indicates the cross-sectional area of ​​the oil storage tank when viewed from above.

[0149] In one specific embodiment, the first oil quantity monitoring module includes:

[0150] The theoretical oil volume calculation module is used to calculate the theoretical oil volume V of the oil tank at the current oil temperature using the following formula. 油算 for:

[0151] V 油算 =V 油0 +αtV 本

[0152] In the formula, V 油0 V represents the standard oil volume in the oil tank at 0℃, t represents the oil temperature sampling value, and V represents the standard oil volume in the tank at 0℃. 本 This represents the total transformer oil volume in the oil conservator at 0℃.

[0153] In one specific embodiment, the system further includes:

[0154] The historical oil volume storage module is used to store the real-time oil volume of the oil tank as historical oil volume data at the corresponding oil temperature and ambient temperature in the historical oil volume database when it is detected that there is no historical oil volume at the same oil temperature and ambient temperature as the real-time oil volume. If the first oil volume difference between the real-time oil volume and the theoretical oil volume of the oil tank does not trigger an oil level abnormality alarm, the real-time oil volume of the oil tank is stored as historical oil volume data at the corresponding oil temperature and ambient temperature in the historical oil volume database.

[0155] The historical oil volume calculation module is used to call the historical oil volume at the oil temperature and ambient temperature that is closest to the real-time oil volume in the historical oil volume database, and obtain the corresponding interpolated historical oil volume as the historical oil volume by interpolation calculation.

[0156] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working process of the system described above can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0157] In the several embodiments provided by this invention, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0158] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0159] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0160] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A digital oil level monitoring method for transformers, characterized in that, Includes the following steps: Obtain the real-time oil level in the oil tank; The real-time oil level is compared with a preset oil level threshold range. If the real-time oil level is within the preset oil level threshold range, proceed to the next step. If the real-time oil level is not within the preset oil level threshold range, an oil level abnormality alarm is issued. Obtain the real-time oil level in the oil storage tank; Calculate the theoretical oil volume of the oil tank at the current oil temperature, obtain a first oil volume difference between the real-time oil volume and the theoretical oil volume, and determine whether the first oil volume difference is greater than a preset first oil volume difference threshold. If the first oil volume difference is greater than the preset first oil volume difference threshold, an oil level abnormality alarm is issued; if the first oil volume difference is not greater than the preset first oil volume difference threshold, proceed to the next step. The specific steps for calculating the theoretical oil volume of the oil tank at the current oil temperature include: The theoretical oil volume V of the oil tank at the current oil temperature is calculated using the following formula. 油算 for: V 油算 = V 油0 +αtV 本 In the formula, V 油0 V represents the standard oil volume in the oil tank at 0℃, t represents the oil temperature sampling value, and V represents the standard oil volume in the tank at 0℃. 本 α is the total transformer oil volume in the oil conservator at 0℃, and α is the coefficient of thermal expansion of the transformer oil. The process involves obtaining a second oil volume difference between the real-time oil volume of the oil tank and the historical oil volume at the same current oil temperature and ambient temperature. It then determines whether the second oil volume difference is greater than a preset second oil volume difference threshold. If the second oil volume difference is greater than the preset second oil volume difference threshold, an oil level anomaly alarm is triggered. If the second oil volume difference is not greater than the preset second oil volume difference threshold, the process returns to the step of obtaining the real-time oil level of the oil tank. When it is detected that there is no historical oil volume in the historical oil volume database that has the same oil temperature and ambient temperature as the real-time oil volume, if the first oil volume difference between the real-time oil volume and the theoretical oil volume of the oil tank does not trigger an oil level abnormality alarm, the real-time oil volume of the oil tank is stored as historical oil volume data at the corresponding oil temperature and ambient temperature in the historical oil volume database. The historical oil volume database is accessed based on the oil temperature and ambient temperature closest to the real-time oil volume. The interpolated historical oil volume is then used as the historical oil volume.

2. The digital oil level monitoring method for transformers according to claim 1, characterized in that, The specific steps for obtaining the real-time oil level in the oil storage tank include: The oil pressure in the oil tank is measured by a digital oil level gauge, and the real-time oil level H in the oil tank is calculated using the following formula. 油 : H 油 = P(1+αt) / ρ 油 g In the formula, P is the oil pressure measured by the digital oil level gauge, t is the oil temperature measured, and ρ is the oil pressure measured by the digital oil level gauge. 油 ρ is the density of transformer oil at 0℃, and g is the acceleration due to gravity.

3. The digital oil level monitoring method for transformers according to claim 2, characterized in that, When the oil storage tank adopts a horizontal cylindrical tank structure, the steps for obtaining the real-time oil volume of the oil storage tank specifically include: The per-unit value of the oil level in the oil tank is calculated using the following formula: h = (H 油 -H 底 ) / D In the formula, h is the per-unit value of the oil tank height, H 底 D is the installation height of the pressure sensor relative to the bottom of the oil tank, and D is the diameter of the oil tank. The oil volume ratio in the oil tank is calculated using the following formula: When h < 0.5, the corresponding oil volume ratio at the high oil level h is: When h ≥ 0.5, the corresponding oil volume ratio at the high oil level h is: The real-time oil volume V in the oil tank is calculated using the following formula. 油 for: V 油 =sV 储油柜 =πsR 2 L In the formula, s is the proportion of oil in the oil tank, and V 储油柜 R is the total volume of the oil tank, R is the radius of the oil tank, and L is the length of the oil tank. When the oil storage tank adopts a vertical corrugated oil storage tank structure, the steps for obtaining the real-time oil volume of the oil storage tank specifically include: The real-time oil volume V of the oil tank is obtained through the following formula. 油 : V 油 =S 俯 H 油 = S 俯 P(1+αt) / ρ 油 g In the formula, S 俯 This indicates the cross-sectional area of ​​the oil storage tank when viewed from above.

4. A digital oil level monitoring system for transformers, characterized in that, include: The oil level acquisition module is used to acquire the real-time oil level height of the oil tank; The oil level monitoring module is used to compare the real-time oil level height with a preset oil level height threshold range. If the real-time oil level height is within the preset oil level height threshold range, the oil quantity acquisition module is executed. If the real-time oil level height is not within the preset oil level height threshold range, an oil level abnormality alarm is issued. The oil quantity acquisition module is used to acquire the real-time oil quantity of the oil storage tank. The first oil level monitoring module is used to calculate the theoretical oil level of the oil tank at the current oil temperature, obtain the first oil level difference between the real-time oil level and the theoretical oil level, determine whether the first oil level difference is greater than a preset first oil level difference threshold, and if the first oil level difference is greater than the preset first oil level difference threshold, an oil level abnormality alarm is issued; if the first oil level difference is not greater than the preset first oil level difference threshold, the second oil level monitoring module is executed. The first oil level monitoring module includes: The theoretical oil volume calculation module is used to calculate the theoretical oil volume V of the oil tank at the current oil temperature using the following formula. 油算 for: V 油算 = V 油0 +αtV 本 In the formula, V 油0 V represents the standard oil volume in the oil tank at 0℃, t represents the oil temperature sampling value, and V represents the standard oil volume in the tank at 0℃. 本 α is the total transformer oil volume in the oil conservator at 0℃, and α is the coefficient of thermal expansion of the transformer oil. The second oil level monitoring module is used to obtain the second oil level difference between the real-time oil level of the oil tank and the historical oil level at the same current oil temperature and ambient temperature, and to determine whether the second oil level difference is greater than a preset second oil level difference threshold. If the second oil level difference is greater than the preset second oil level difference threshold, an oil level abnormality alarm is issued. The historical oil volume storage module is used to store the real-time oil volume of the oil tank as historical oil volume data at the corresponding oil temperature and ambient temperature in the historical oil volume database when it is detected that there is no historical oil volume at the same oil temperature and ambient temperature as the real-time oil volume. If the first oil volume difference between the real-time oil volume and the theoretical oil volume of the oil tank does not trigger an oil level abnormality alarm, the module will store the real-time oil volume of the oil tank as historical oil volume data at the corresponding oil temperature and ambient temperature in the historical oil volume database. The historical oil volume calculation module is used to call the historical oil volume at the oil temperature and ambient temperature that is closest to the real-time oil volume in the historical oil volume database, and obtain the corresponding interpolated historical oil volume as the historical oil volume by interpolation calculation.

5. The digital oil level monitoring system for transformers according to claim 4, characterized in that, The oil level acquisition module is specifically used to measure the oil pressure in the oil tank using a digital oil level gauge, and to calculate the real-time oil level height H of the oil tank using the following formula. 油 : H 油 = P(1+αt) / ρ 油 g In the formula, P is the oil pressure measured by the digital oil level gauge, t is the oil temperature measured, and ρ is the oil pressure measured by the digital oil level gauge. 油 ρ is the density of transformer oil at 0℃, and g is the acceleration due to gravity.

6. The digital oil level monitoring system for transformers according to claim 5, characterized in that, When the oil storage tank adopts a horizontal cylindrical tank structure, the oil quantity acquisition module specifically includes: The per-unit value calculation module is used to calculate the per-unit value of the oil level at the height of the oil tank using the following formula: h = (H 油 -H 底 ) / D In the formula, h is the per-unit value of the oil tank height, H 底 D is the installation height of the pressure sensor relative to the bottom of the oil tank, and D is the diameter of the oil tank. The oil volume ratio calculation module is used to calculate the oil volume ratio of the oil tank using the following formula: When h < 0.5, the corresponding oil volume ratio at the high oil level h is: When h ≥ 0.5, the corresponding oil volume ratio at the high oil level h is: The real-time oil volume calculation module is used to calculate the real-time oil volume V of the oil tank using the following formula. 油 for: V 油 =sV 储油柜 =πsR 2 L In the formula, s is the proportion of oil in the oil tank, and V 储油柜 R is the total volume of the oil tank, R is the radius of the oil tank, and L is the length of the oil tank. When the oil storage tank adopts a vertical corrugated oil storage tank structure, the steps for obtaining the real-time oil volume of the oil storage tank specifically include: The real-time oil volume V of the oil tank is obtained through the following formula. 油 : V 油 =S 俯 H 油 = S 俯 P(1+αt) / ρ 油 g In the formula, S 俯 This indicates the cross-sectional area of ​​the oil storage tank when viewed from above.

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